Determination of phytosiderophores by anion-exchange chromatography with pulsed amperometric detection

Phytosiderophores of the mugineic acid family are separated by anion-exchange HPLC using NaOH gradient elution. Separation of mugineic acid (MA), 2'-deoxymugineic acid (DMA), 3-hydroxymugineic acid (HMA) and 3-epi-hydroxymugineic acid (epi-HMA) is obtained within 15 min. Detection of the underivatised phytosiderophores is performed using pulsed amperometric detection (PAD) at pH 13. The sensitivity of the detection increases in the order DMA < MA < HMA < epi-HMA and respective detection limits of 5 microM (DMA), 1 microM (MA) and < 0.5 microM (HMA, epi-HMA) are achieved. PAD is discussed in comparison with the well-established fluorimetric detection method after post-column derivatisation with ortho-phthaldialdehyde. The main advantage of PAD is the simplicity of the method (no derivatisation) and the high sensitivity for hydroxylated mugineic acids. The method is used for the determination of phytosiderophores in root washings of iron-deficient and non-deficient wheat and barley plants.     

阴离子交换色谱法测定硫磺熏制姜中亚硫酸盐

建立了阴离子交换色谱分离、抑制型电导检测分析硫磺熏制生姜(简称硫磺姜)中亚硫酸盐的方法。使用NJ-SA-4A阴离子交换分析柱,淋洗液为1.92mmol/L Na2CO3-1.80mmol/L NaHCO3-2%(体积分数)丙酮。通过在样品提取液中加入三乙醇胺,有效地维持了亚硫酸盐的稳定性、并能提高方法的选择性。SO23-在0.02～2.00mg/L范围内线性良好,相关系数为0.9998,峰面积的相对标准偏差为1.9%。方法的检出限为0.015mg/L,加标回收率为84.0%～93.5%。该方法为生姜的市场监测提供了有效的方法。     

Determination of impurities in clodronic acid by anion-exchange chromatography

A validated ion chromatographic method for the determination of anionic impurities in clodronic acid or disodium clodronate is described. Separations are performed by using an anion-exchange column (IonPac AS5) and a sodium hydroxide gradient. Impurities are detected by suppressed conductivity without the need for derivatisation. The most important variable affecting the separation was shown to be the column temperature.     

Determination of tylosin in feeds by liquid chromatography with solid-phase extraction

A method was developed for the determination of tylosin in feeds. The method involves extraction of tylosin with methanol, concentration under a stream of nitrogen, and cleanup using Phenomenex C18 solid-phase extraction cartridge. Analyte separation and quantitation were achieved by gradient reversed-phase liquid chromatography and UV absorbance at 285 nm with a reference wavelength of 320 nm with column temperature of 45 degrees C. Average spike recoveries for samples prepared at 4 spiking levels (22.7, 181, 907, and 1000 g/ton) were 111.0, 94.9, 96.2, and 98.6%, respectively. The overall method precision at each of the 4 spiking levels was < or = 7.85% relative standard deviation. The limits of detection and quantitation (g/ton) were 2.16 and 7.20 g/ton, respectively.     

Determination of aminosaccharides by high-performance anion-exchange chromatography with pulsed amperometric detection

High-performance anion-exchange chromatography (HPAC) was used for the determination of aminosaccharides in microbial polymers, chitin, animal waste, sewage sludge, plant residues and soil. The aminosaccharides, galactosamine, mannosamine and glucosamine were separated on a strong anion-exchange column with 1OmM sodium hydroxide as the eluent and determined by pulsed amperometric detection (PAD). The HPAC-PAD methodology was compared with high-performance liquid chromatography (HPLC) with refractive index detection (RI) in terms of selectivity and sensitivity for aminosaccharides. The results indicate that HPAC-PAD required less sample preparation, and was more precise and nearly two orders of magnitude more sensitive than HPLC-RI. HPAC-PAD was not subject to matrix interferences and was highly selective for aminosaccharides. More than 3% of the total nitrogen in alfalfa, and 20% of that in straw, was found to be present as aminosaccharides.     

超高效液相色谱-串联质谱法测定饲料中的维吉尼霉素M1

建立了饲料中维吉尼霉素M1的超高效液相色谱-串联质谱(UPLC-MS/MS)分析测定方法。样品用乙腈-0.2%(v/v)甲酸水溶液(8:2, v/v)超声提取两遍后,通过UPLC-MS/MS进行分析,以BEH C18色谱柱为分析柱,乙腈-0.3%(v/v)甲酸水溶液（35:65, v/v）为流动相,采用电喷雾电离正离子模式,以多反应监测模式进行定性和定量分析。在0.3～226.6 μg/L范围内线性关系良好(相关系数r=0.9995)。维吉尼霉素M1的检出限和定量限分别为2 μg/kg和7 μg/kg,平均回收率为82.6%～102.7%,相对标准偏差为0.9%～10.5%。结果表明,该方法具有操作简单、准确度和灵敏度高、重现性好的特点,适合用于检测饲料中维吉尼霉素M1的含量。     

Determination of penicillin G in feeds by liquid chromatography with solid-phase extraction

A liquid chromatographic method was developed for the determination of penicillin G in feeds. The method involves extraction of penicillin G with methanol, concentration under a stream of nitrogen, and cleanup using Phenomenex Strata-X solid-phase extraction cartridge. Analyte separation and quantification were achieved by gradient reversed-phase liquid chromatography and ultraviolet absorbance at 230 nm. Average spike recoveries for samples prepared at 3 spiking levels (25, 50, and 200 g/ton) were 96.3, 92.1, and 88.6%, respectively. The overall method precision at each of the 3 spiking levels was < or = 5.39% relative standard deviation. The limits of detection and quantititation (g/ton formulation) were 3.89 and 13.0 g/ton, respectively.     

Determination of saccharides by high performance anion-exchange chromatography with pulsed amperometric detection

Summary High performance anion-exchange chromatography (HPAC) coupled with pulsed amperometric detection (PAD) under alkaline conditions (pH 13) separates neutral saccharides based upon their molecular size, saccharide composition, and glycosidic linkages. Carbohydrates were detected by oxidation with a gold-working electrode. HPAC-PAD was compared to high performance liquid chromatography (HPLC) with refractive index (RI) detection in terms of selectivity and sensitivity of saccharides. The results indicate that HPAC-PAD was more precise, two orders of magnitude more sensitive (pmol range) and gives better resolution of saccharides than HPLC-RI. HPAC-PAD required less sample preparation and was not subjected to matrix interferences. The use of HPAC-PAD was applied to the analysis of organic materials (plant residues, animal wastes and sewage sludge) and soil.     

Determination of avilamycin in poultry feeds by liquid chromatography.

Avilamycin was extracted from feed with acetonitrile. Isolation of avilamycin factors from feed matrix interference was accomplished by normal-phase solid-phase extraction with silica as sorbent. Reversed-phase liquid chromatography was subsequently used to separate and quantitate the primary biologically active factors A and B for determination of chemical potency. This method combines specificity for avilamycins A and B in poultry feeds with simple sample preparation that removes matrix interferences. Recoveries of factor A ranged from 93.29 to 97.26%, with precision (relative standard deviation) ranging from 1.1 to 3.4%. Avilamycin factors in feed samples tested ranged from 4.45 to 17.82 micrograms/g for factor A and from 0.80 to 3.18 micrograms/g for factor B.     

Determination of petroleum sulfonates in crude oil by column-switching anion-exchange chromatography

A column-switching anion-exchange chromatography method was described for the separation and determination of petroleum monosulfonates （PMS） and petroleum disulfonates （PDS） in crude oil that was simply diluted with the dichloromethane/methanol （60/40）. The high performance liquid chromatography （HPLC） system consisted of a clean-up column and an analytical column, which were connected with two six-port switching valves. Detection of petroleum sulfonates was available and repeatable. This method has been successfully applied to determine PMS and PDS in crude oil samples from Shengli oil field.     

Determination of guanidino compounds by anion-exchange chromatography and amperometric detection

Guanidino compounds were separated and determined by anion-exchange chromatography and electrochemical detection using a basic aqueous eluent and a nickel working electrode. It was found necessary to use a sample clean-up procedure prior to chromatographic analysis of uremic dialysate and serum samples. The effect of eluent hydroxide concentration on the retention of guanidino compounds was studied. Quantitative calibration showed that working curves were non-linear. Electrochemical detection for guanidino compounds with a nickel working electrode, while not selective, has high detection sensitivity. Detection limits for guanidino compounds ranged from 3 to 12 pmol.     

液相色谱-电喷雾电离三重四级杆质谱测定畜禽肝脏中维吉尼亚霉素M1的残留量

建立了动物肝脏组织中维吉尼亚霉素M1残留的液相色谱-电喷雾电离三重四级杆质谱(LC-ESI-MS/MS)的测定方法。样品经0.2 mol/L NH4H2PO4和乙酸乙酯提取,分散型固相萃取PSA填料净化,采用正离子扫描多反应监测(MRM)模式下液质联用仪进行定性和定量分析。该方法省去耗时的固相萃取过程,回收率在67.2%～90.3%之间,RSD<10.0%;检测限为0.5μg/kg,定量限为1.0μg/kg。     

Determination of several sugars in serum by high-performance anion-exchange chromatography with pulsed amperometric detection

In this paper, a sensitive, simple and direct method for simultaneous determination of glucose, ribose, isomaltose and maltose in serum sample by high-performance anion-exchange chromatography coupled with integrated pulsed amperometric detection was developed. The four target analytes were easily and completely separated on an anion-exchange column at a flow-rate of 0.25 mL/min by binary step gradient elution in about 16 min and the two eluents were deionized water and 500 mM sodium hydroxide, respectively. The separated four analytes were detected directly by using a gold electrode and quadruple-potential waveform integrated pulsed amperometry without derivatization. Under the optimized conditions, when the injection volume was 25 microL, the detection limits (signal-to-noise ratio equal to 3) for glucose, ribose, isomaltose and maltose were 0.92, 7.50, 12.9 and 10.3 ng/mL, respectively. The calibration graphs of peak area for the four analytes were linear over two to three orders of magnitude with correlation coefficients greater than 0.998. R.S.D. of peak areas of the four analytes for five determinations were no more than 5.6%. The analytical method had been applied to the determination of glucose, ribose, isomaltose and maltose in real serum samples and good results with low relative standard deviation not more than 5.3% were obtained. The accuracy of the proposed method was tested by recovery measurements on spiked samples and good recovery results (98.1-107.9%) were obtained.     

Determination of saccharides in biological materials by high-performance anion-exchange chromatography with pulsed amperometric detection

High-performance anion-exchange chromatography (HPAEC) coupled with pulsed amperometric detection (PAD) under alkaline conditions (pH 9-13) separates aminosaccharides, neutral saccharides and glycuronic acids based upon their molecular size, saccharide composition and glycosidic linkages. Carbohydrates were extracted by utilizing 0.5 M H2SO4 (neutral monosaccharides), 0.25 M H2SO4 coupled with enzyme catalysis (glycuronic acids) and 3 M H2SO4 (aminosaccharides). Solid-phase extraction with strong cation and strong anion resins was used to partition the cationic aminosaccharides and anionic glycuronic acids and to deionize acid extracts for neutral saccharides. Separation was conducted on a medium-capacity anion-exchange column (36 mequiv.) utilizing sodium hydroxide (5-200 mM and sodium acetate (0-250 mM) as the mobile phase. The saccharides were detected by oxidation at a gold working electrode with triple-pulsed amperometry. HPAEC-PAD was found superior to high-performance liquid chromatography with refractive index (RI) detection for neutral monosaccharides and aminosaccharides and to low-wavelength UV detection for glycuronic acids in terms of resolution and sensitivity. HPAEC-PAD was not subject to interferences as was the case for low UV detection (210 nm) or RI analyses and was highly selective for mono- and aminosaccharides and glycuronic acids. The use of HPAEC-PAD was applied for the determination of the saccharide composition of organic materials (plant residues, animal wastes and sewage sludge), microbial polymers and soil.     

Determination of nicarbazin and clopidol in poultry feeds by liquid chromatography

A rapid and very effective analytical procedure for the simultaneous liquid chromatographic determination of two coccidiostats, clopidol (CLOP) and nicarbazin (NICA), in poultry feeds was developed and tested. The ground feed samples were extracted using aqueous dimethylformamide after moistening with water. Co-extracted feed constituents were removed with a solid-phase extraction alumina-basic column and the eluates were directly analyzed on an ODS column (250x4.6 mm, 5 microm) with acetonitrile-0.01 M acetate buffer (pH 4.6) as eluent. UV detection of CLOP and the 4,4'-dinitrocarbanilide portion of NICA was carried out at 265 and 345 nm, respectively. The mean recovery from NICA spiked samples was 95% with a RSD of 4% in a concentration range of 2-150 mg/kg while for CLOP it was 98% with a RSD of 5% in a concentration range of 5-150 mg/kg. The limits of detection of NICA and CLOP in feed, based on a detector signal-to-noise ratio of 3, were estimated to be 1 mg/kg and 2.5 mg/kg, respectively, and the lowest levels tested in feeds by this procedure were 2 mg/kg and 5 mg/kg, respectively.     

Determination of sugars and alditols in tobacco with high performance anion-exchange chromatography

Sugars, alditols, and alcohols in tobacco products were quantified utilizing a method of high-performance anion-exchange chromatography-pulsed amperometric detection (HPAEC-PAD). The optimized analytical method can be used to classify different tobaccos and control the quality of tobaccos. To substantiate the applicability of the method, the analysis of 27 tobacco samples with satisfactory linearity, repeatability, and accuracy had been demonstrated. Compared with some other analytical methods for tobacco, the HPAEC-PAD method provided a simple and powerful tool for the analysis of not only sugars but also alcohols in tobacco extracts.     

Determination of chlortetracycline residues in tissues using high-performance liquid chromatography with fluorescence detection

A method is described for the determination of chlortetracycline residues in tissue samples. The samples were extracted into a hydrochloric acid - glycine solution and the extracts concentrated and purified on cyclohexyl-bonded reversed-phase cartridges. Any chlortetracycline present was converted to iso-chlortetracycline at pH 12, which was then separated from interfering compounds on a reversed-phase polymeric column using high-performance liquid chromatography with fluorescence detection. The detection and determination limits of the assay were 20 and 50 ng g-1, respectively, making it suitable for statutory residue testing purposes.